Ticket field changed events for custom fields?

// code to be executed when the priority of the ticket is changed.

{

var event_data = event.helper.getData();

console.log(event.type + " changed from " + event_data.old + " to " + event_data.new);

};

//client.events.on("ticket.priorityChanged", propertyChangeCallback);

client.events.on("ticket.customField.my_custom_field", propertyChangeCallback);

Thanks.